We have had problems with our Ravenheat CSI 85AT almost since it was fitted 3 years ago. (Many of the internal joints were leaking when the boiler was fitted. We replaced a 20 year old Worcester Heatslave, which had given us no problems but was underpowered after extending.
Within a couple of months, the fan failed. The bearing had disintegrated to dust.
I contacted Ravenheat, who sent out a young girl to inspect the boiler. She admitted she had no gas or heating qualifications - then tried to say it was my fault, as I had taken the fan out to check it. I have been a heating engineer for 40 years, so that didn't go down well with me. Ravenheat have refused to come out again or offer any help.
Now boiler trips out all the time, or won't fire up at all. Currently no heating or hot water. Got a new thermistor to fit, so will see what happens.
We do have a fault that no one else seems to have - the heating will switch itself on (though its turned off on the controls), usually in the middle of the night!
Just feel like ripping it out and trying to find something reliable.
Despite all my years in the business, I still can't get it to work reliably - must be the worst boiler ever made.